Chevrolet 10 Series 1968, Service Manual, Page: 457 / 713

ENGINE-ELECTRICAL 6Y-32
MOUNTING
SCREW
TRANSISTOR TR3
Fig. 2 4 i— Pulse A m p lifie r Panel Board
having a
1
-
1/2
volt cell, which is the type usually found
in service stations, is recommended. The low range
scale on the ohmmeter should be used except where
specified otherwise.
A 25 watt soldering gun is recommended, and a 60%
tin 40% lead solder should be used when re-soldering.
Avoid excessive heat which may damage the panel board.
CHECKING CHECKING CHECKING CHECKING CHECKING
DIODE D1 RESISTOR R3 RESISTOR R4 RESISTOR R5 RESISTOR R2
CHECKING
f
CHECKING TRIGGER CHECKING
RESISTOR R1 _____
J_
TRANSISTOR TR3 CAPACITOR Cl
[
u n s o l d e r
]
Fig. 2 5 i—Pulse A m plifier Component- Checks
IG N ITIO N PULSE AMPLIFIER
Fig. 261 — Pulse A m plifier Internal C ircu itry
Chip away any epoxy involved, and apply new epoxy which
is commercially available.
In order to check the panel board assembly, it is nec-
essary to unsolder at the locations indicated in Figure 5i
the two capacitors C2 and C3. In all of the following
checks, connect the ohmmeter as shown and then reverse
the ohmmeter leads to obtain two readings. Internal
circuitry of the amplifier is shown in Figure 26i.
1. Transistors TR l and TR2: Check each transistor by
referring to Figure 27i. If both readings in Step 1
are zero, the transistor is shorted. If both readings
in Step 2 are zero, the transistor is shorted; and if
both readings are infinite, the transistor is open.
Interpret Step 3 the same as Step 2.
2. Trigger Transistor TR3: If both readings in Step 1
are zero, the transistor is shorted. If both readings
in Step 2 are zero, the transistor is shorted; and if
both readings are infinite, the transistor is open.
Interpret Step 3 the same as Step 2.
3. Diode Dl: If both readings are zero, the diode is
shorted; and if both readings are infinite, the diode is
open.
4. Capacitor Cl: If both readings are zero, the capaci­
tor is shorted.
5. Capacitors C2 and C3: Connect the ohmmeter across
each capacitor (not illustrated). The capacitor is
shorted if both readings are zero.
6 . Resistor R l: The resistor is open if both readings
are infinite.
7. Resistor R2: Use an ohmmeter scale on which the
1800 ohm value is within, or nearly within, the mid­
dle third of the scale. If both readings are infinite,
the resistor is open.
8 . Resistor R3: Use an ohmmeter scale on which the
680 ohm value is within, or nearly within, the middle
CHEVROLET TRUCK SERVICE MANUAL